An SNS account generally uses a method based on a cellular phone number in the present, and creation of an account is accomplished through one Short Message Service (SMS) authentication for one cellular phone number. In this method, although a process related to creation of an account is clear, a process related to expiry and deletion of an account is relatively unclear.
When a specific user using an account changes a phone number, a friend knowing only a previous phone number and ignorant, of the new phone number may possibly make a wrong connection if another person acquires the corresponding phone number and registers an account. A technique of tracing a phone number based on a server is required to prevent this problem.
In addition, if an SMS account is created using the new phone number, content of previous dialog windows cannot be transferred. Although the dialog windows can be downloaded as a file, this is merely preservation of data, and continuity of a dialog accomplished in the open windows cannot be provided.